It seems that PHP-FPM is not running now
[Wed Sep 25 11:16:30.718870 2019] [proxy:error] [pid 3565:tid 139884392015616] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/bitnami/php/var/run/wordpress.sock (wordpress-fpm) failed
[Wed Sep 25 11:16:30.718882 2019] [proxy_fcgi:error] [pid 3565:tid 139884392015616] [client 220.127.116.11:54442] AH01079: failed to make connection to backend: httpd-UDS
Can you check the status of the services and start it if it's stopped?
sudo /opt/bitnami/ctlscript.sh status
sudo /opt/bitnami/ctlscript.sh start php-fpm
Does it return any error message?
What parameter did you change and in which file?